This invention relates to the field of automatic clothes dryers. In particular, it relates to the lint filter system and a signal for indicating that the lint filter needs to be checked for lint build-up.
The automatic clothes dryer employs a lint filter. The heated drying air from the clothes dryer passes through the tumbling chamber or rotating drum containing the clothes to be dried. This spent drying air, after leaving the chamber, passes through the lint filter which traps and holds any lint or solid particles suspended in the exhausted air. After periods of drying use, usually one or more drying cycles, the lint filter accumulates a coating of trapped lint and if not cleaned, the lint filter may become clogged. This becomes a resistance to air flow through the dryer which interferes with efficient operation.
There has been devised a number of devices for clothes dryers in the prior art to detect a clogged filter and warn the operator of the condition; or in the alternative, to shut down the heat source of the dryer during its drying cycle if the clogged filter condition is detected. In U.S. Pat. No. 3,286,508, the condition of the filter is determined by sensing variations in the static pressure, or in U.S. Pat. No. 2,941,308, air flow volume through the filter is sensed and if lint buildup is present, the drying unit is shut down and a signal is given. U.S. Pat. No. 3,484,772 senses the condition of the filter by shining a light through it and if the filter is coated with lint to such a degree to diminish the light intensity, a signal is given by a flashing light to alert the operator of the condition. And, U.S. Pat. No. 4,206,552 utilizes a sensor system that measures the temperature of the air entering the drying compartment and compares it with the temperature of the moisture laden air leaving the drying compartment. A control element interprets this information of sensed temperature and if the temperature differential exceeds a value, it indicates a clogged filter and deactivates the drying apparatus. And, in U.S. Pat. No. 4,763,425, the microprocessor control for the dryer includes a reminder which flashes a CLEAN FILTER signal on the control panel when selecting one of the "on/select" touch pads of the operator's control.
The prior art has shown a number of lint filter systems in which a signal of one kind or another is incorporated to alert the operator to a clogged condition of the filter.